html,
body {
  height: 100%;
}
.clearfix:after {
  content: '.';
  display: block;
  height: 0;
  visibility: hidden;
  clear: both;
}
.clearfix {
  *zoom: 1;
}
.placeholder {
  display: inline-block;
  width: 0;
  font-size: 0;
  height: 100%;
  vertical-align: middle;
}
